Some portable electronic devices such as cellular telephone devices and the like include: an operation unit that is configured to include first keys assigned with nonnumeric characters but not numeric characters, and second keys assigned with the nonnumeric characters and the numeric characters; a display unit that displays at least one of the nonnumeric characters and the numeric characters in accordance with an operation of the operation unit; and a control unit that controls content displayed on the display unit (for example, see Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2006-293965